2 Aerodynamics
127
object, the Mach cone is cone-shaped). In the upstream of the Mach
wave, the flow is not affected, and in the downstream of the Mach
wave, the flow is disturbed. Let the half vertex angle of the Mach cone
be called the Mach angle μ. According to the geometric relationship,
the normal velocity of the airflow perpendicular to the Mach line is
sound speed a, which has
sin(μ) =
V n
V
=
a
V
, μ = arcsin
a
V
= arcsin
1
Ma
As shown in Fig. 2.62, the control body shown in Fig. 2.63 is taken
around the CL line on the Mach wave, which can be seen from the
continuous equation
m = ρV n = (ρ + dρ)(V n + dV n )
Fig. 2.62 Control body on Mach wave front
Fig. 2.63 Speed decomposition of over-control body
127
object, the Mach cone is cone-shaped). In the upstream of the Mach
wave, the flow is not affected, and in the downstream of the Mach
wave, the flow is disturbed. Let the half vertex angle of the Mach cone
be called the Mach angle μ. According to the geometric relationship,
the normal velocity of the airflow perpendicular to the Mach line is
sound speed a, which has
sin(μ) =
V n
V
=
a
V
, μ = arcsin
a
V
= arcsin
1
Ma
As shown in Fig. 2.62, the control body shown in Fig. 2.63 is taken
around the CL line on the Mach wave, which can be seen from the
continuous equation
m = ρV n = (ρ + dρ)(V n + dV n )
Fig. 2.62 Control body on Mach wave front
Fig. 2.63 Speed decomposition of over-control body